Poly(aryl ether ketones) are a relatively new class of engineering polymers. These polymers are crystalline and exhibit an excellent combination of properties, i.e. excellent thermal and hydrolytic stability, high strength and toughness, excellent wear and abrasion resistance and excellent solvent resistance. Thus, articles molded from poly(aryl ether ketones) have utility where high performance is required. Representative materials of this class are the polymers (1) and (2). ##STR1##
To achieve the desired combination of properties, high molecular weight poly(aryl ether ketones) are necessary. These high molecular weight poly(aryl ether ketones) have a narrow processing latitude and require very high processing temperatures (about 400.degree. C.) during molding. Many materials which could act as plasticizer or processing aid for the poly(aryl ether ketones) are not stable at such a high processing temperature. Also, most polymers do not have adequate thermal stability at such processing temperatures to allow them to be blended with the poly(aryl ether ketone).
Thus, there is a desire to improve the processing of poly(aryl ether ketones), particularly in the presence of fibers and fillers which decrease the processing range.
Poly(arylene sulfides), e.g. polyphenylene sulfides (hereinafter abbreviated "PPS") are high performance, crystalline engineering plastics; the materials of the PPS class have excellent heat resistance, good hydrolytic and chemical resistance, and high rigidity. These products compare favorably with other engineering polymers such as the nylons, the polycarbonates, polyacetals and poly(butylene terephthalate). Moreover, these polymers are relatively inexpensive and have very good abrasion resistance. PPS resins, however, have a serious drawback: they have poor toughness. Even the recently prepared versions of PPS that are linear, also show poor impact strength and elongation in the crystalline state. Thus, the need exists to improve the overall mechanical properties of PPS.
Poly(ether imides) are also commercially available. They are amorphous thermoplastic polymers with high heat resistance, high strength and modulus, and high dielectric strength. Polyetherimides can be molded into a variety of articles. However, the ultimate use temperature and solvent resistance of the polyetherimides is not acceptable in end-use applications where such properties are required. Hence, improvement of these deficiencies without essentially affecting other properties of the poly(ether imides) is highly desirable.
Poly(aryl ether) resins are tough rigid high strength thermoplastics which maintain their properties over a wide temperature range of from -15.degree. F. to above 300.degree. F. They have a high continuous use temperature of about 300.degree. F. They are hydrolytically stable and have excellent mechanical and electrical properties which allows them to be molded into a variety of articles.
The poly(aryl ethers) (hereinafter referred to as PAE's) presenting the greatest practical interest are those that contain the sulfone group. Thus, poly(aryl ether sulfones) (3) and (4) ##STR2## are commercially available tough thermoplastic materials. They possess a number of attractive features such as excellent high temperature resistance, good electrical properties, and very good hydrolytic stability. Polymer (3) is available from Imperial Chemical Industries, Ltd. under the trademark of Victrex.RTM. Poly(ether sulfone). It is produced by the polycondensation of 4,4,-dihydroxydiphenyl sulfone with 4,4,-dichlorodiphenyl sulfone as described in, for example, Canadian Patent No. 847,963. The resin contains no aliphatic moeities and has a heat deflection temperature of approximately 210.degree. C. Material (4) is available from Amoco Performance Products, Inc., under the trademark of UDEL.RTM.. It has a heat deflection temperature of about 180.degree. C., and is made via the nucleophilic polycondensation of bisphenol-A di-sodium salt with 4,4 -dichlorodiphenyl sulfone, as described in U.S. Pat. No. 4,108,837.
Poly(aryl ether) resins are highly resistant to mineral acids, and salt solutions but when exposed to polar organic solvents, they readily stress crack.
Obviously, if it were possible to improve the environmental and stress-crack resistance of the PAE's, a truly remarkable class of products would be at hand.